Staple driving means for portable pneumatic staplers



STAPLE DRIVING MEANS FOR PORTABLE' PNEUMATIC STAPLERS Filed Aug. 23.1950 /2 1J I'IGQI. 2

Patented Feb. 19, 1952 STAPLE DRIVING .MEANS FOR PORTABLE PNEUMATICSTAPLERS Albert G. Juilfs, Newtown, Ohio, assigner to Senco Products,Inc., Cincinnati, Ohio, a corporation of Ohio- Application August 23,1950, serial No. 181,025

'12 claims. (C1. 1 49 My invention relates to a portable pneumaticstapler primarily designed for stapling upholstery to the interior ofautomobile bodies, and in particular this invention relatesto novelstaple drive mechanism for suchy a stapler. In my cope-ridingapplication entitled `Staple Magazine and Feed Means for PneumaticStaplers, filed November 23, 1949, Serial No. .128 941, and issued as U.S. Letters'Patent No. 2,585,941 on February 19, 1952, I have disclosed astaple feed mechanism. Reference is also made to my copendingapplications as follows: Staple Drive Mechanism for Portable PneumaticStaplers, filed of even date herewith and bearing Serial No. 181,023;Staple Feed Mechanism for Portable Pneumatic Staplers, filed of evendate herewith, bearing Serial No. 181,024, and issued as U. S. .LettersPatent No. 2,685,942 on February 19, 1952; and Valve Control System`4for Portable Pneumatic Stapler, led of even date herewith, bearingSerial No. 181.026, and issued as4 U. S. Letters Patent No. 2,585,940 onFebruary 19, 1952.

A principal object of the present invention is to provide a portablepneumatic stapler 4in which the staple driving means are so arrangedthat the stapler can be used to drive staples in corners and crevicesgenerally diicult to reach.

A. further object of this invention is to provide staple driving meanswhich can be easily and quickly disassembled in order to clear the.staple gun of Iiamrned or bent staples.

Another object of this invention is to provide staple driving means ofsuch type that the nose through which the staples are discharged and thedriver for driving the staples can be quickly and easily changed withouthaving to make any change in the stroke of the piston to which thestaple driver is fastened.

A further object of the present invention is to provide a portablepneumatic stapler which is rugged and which can be manufactured cheaply.

These and other objects and advantages of my invention will becomeapparent to those skilled in the art during the course of the followingdescription and from reference to the accompanying drawings in whichlike numerals are used to designate like parts throughout the same, andin which,

Figure 1 is a plan view of a portable pneumatic stapler constructedaccording to my invention and with parts broken away and parts shown insection in order to show the internal mechanism of the stapler,

Figure 2 is a cross section of the stapler shown 2 A in Figure 1 takenon the section line 2--2 of Figure 1, Y

Figure 3. is a cross section of a portion of the forward end of thestapler taken on the section line 3--3 of Figure 2, and

Figure 4 is a plan view of a strap which forms the top wall of thestaple driving guide for driveway..

. Briey,inlthe practice .of my invention, a portable pneumatic. staplerincluding a cylinder having la piston is 'actuated by compressed air.The piston activates a staple driver which picks up va staple fromv thefeed kand drives it through the material and into the base to which thematerial is kto be attached. l

The Ypiston is Vactuated by the compressed air in its drive but returnedto its home position by a helical spring.

,In thewall of 'the cylinder carrying the staple driving piston, Iprovide an exhaust or leak vent for permitting the air between thepiston and the base of the cylinder to'exhaust when the piston isvdriven. Y This vent is positioned between the pistonin its retractedposition, that shown in Figure 2, and the other end or base of thecylinder so that it is sealed off as the piston passes the vent and acushion of air is formed between the piston and the end of the gun toabsorb the shock of the movement of the piston. When air of very highpressure is used, this vent should be relatively small, while when verylow air pressure isv used, the Vent should be larger. In order toprovide a gun `or staple driver which may operate on different airpressures, I provide a nipple which is removable from the vent so thatwhen high pressure is used, a nipple having a slight aperture ymay bescrewed into the gun, while in using low pressure a nipple having a,larger aperture may be screwed into the gun.

4v Reierringto the drawings, I provide a cylinder l-locatedin thestapler vhousing 2 and carrying the piston 3. One end of the cylinderlis enclosed yby the plug or cylinder head 4. K There is a staple driver5 pinnedY to the piston 3 which projects beyond the opposite end t ofthe cyl-inn der onto a guiding track l. rlhe end t of the cylinderj'l isclosed by the housing 2. excepting for the track 'l which is closedbythe driver 5. yThe piston 3 is urgedk to its retracted position by thehelicalV spring B`which'is based in an aperture 9 in the housing 2. Thespring 5i is kept in line by rod or pin lll'. also based in the 2 andvaperture 9; This Vrod lil may be .fined to a plug I Gay-just nicelyfitting within the bore or aperture 9. l

Since the portion of the cylinder I between the piston 3 in itsretracted position and the end of the gun is thus sealed, a vent II isprovided in a side wall of the cylinder I and a corresponding vent isprovided in the housing 2. These vents are located between the piston 3in its retracted position and the head 6 to permit the exhaust of theair within the cylinder when the piston is actuated. The vent II ispositioned slightly short of the end S so that as the piston 3 passesthe vent I I, air is entrapped between the piston 3 and the forward endof the gun, thus forming a cushion. In order to permit the use ofdiierent air pressures in actuating vthe gun, I provide a nipple I2having an aperture I3. This nipple is located in the housing vent whichcorresponds to the cylinder vent I I. nipples I2 are provided havingdifferent sized apertures I3 so that the'appropriate nipple may be usedwith the gun, dependingon the air vpressure used to operate the gun.Also thestriking power of a staple gun constructed accordingito myinvention can be easily changed without having to change the airpressure all over the plant. This is a distinct feature of my inventionand one not to be found in other staple guns known to me.

The handle portion I4 of the gun contains a pressure chamber I5, thelower end of which is attached to the compressed air line. The upper endterminates in a passageway I6 which communicates with a chamber I1.Within the chamber I'.' is a valve I8 seated against one end of a.sleeve I9 so as to seal off the interior of this sleeve from thepassageway I 6 and chamber I1. The valve I8 is mounted on a rod 20within-the interior or chamber portion 2| of vthe sleeve I9. There is apassageway 22 which communicates with the chamber 2| and the inlet portof the cylinder I.

Slidablv mounted within the sleeve 2| is a bushing 23 which has aninternal bearingr 24 to accommodate the end of the rod carrying thevalve I8. Within this bearing is a relatively weak coil spring 25 whichurges the rod 2li away from the closed end of the bushing 23. Thebushing 23 terminates in an abutment 26 which is urged from the handleI4 by a relatively strong helical spring 21. I also provide a trigger 28pivoted in the stapler body or housing 2 fo assist in the pressing ofthe operating button 26. Located between the valve I8 and a plug 29, andabout an extension 20a of the rod 20, there is positioned a spring 30.

From the above, it is apparent that as the trigger 28 is squeezed andthe button 26 pressed against the pressure of the spring 21, first ofall the relatively weak spring 25 is depressed, since the pressure inthe chamber I1 (plus the pressure of spring 39) against the valve I 8 isnormally greater than the tension of the spring 25. However, as thespring 25 is further depressed, its tension increases until it bears thepressure of the air in the chamber I1 and spring 30. This opens thevalve I8 slightly and then the spring 25 snaps the valve I8 wide open.This is explained as follows. At the instant the valve member I8 isfirst cracked, air bleeds past the member I8 into the chamber 2|,through the passageway 22 and through a longitudinal groove 32, to bedescribed, where it meets the resistance oiTered by the small groove 32and the piston 3. Pressure then builds up in the chamber 2| (the exhaustport 1I being closed as will be` described) and this pressure helps tocounterbalance the tair Diiierent l 4 pressure in chamber I1 and thetension in spring 30. When this condition exists the compression ofspring 25 serves to force the valve member I8 toits full open positionsuddenly. Such condition comes into existence very soon after the valveis Viirst slightlyU cracked in the manner described. A'It shouldbe'noted that the result will be the same regardless 'of how slowly thetrigger 28 is pulled; all that matters is that the spring 25 is finallyso compressed that the valve is first cracked slightly-the sudden andcomplete opening of the valve will then occur automatically if the otherparts are arranged as described. By this arrangement the operation of mystaple gun is made independent of the touch of the operator; evenandsmooth driving power and operation are thus assured at all times.

The inlet passageway 22 terminates in a port 3| of substantial size.There is a small groove 32 cut in the inner wall of the cylinder I underthe piston 3 in its retracted position which runs to the rear of thepiston 3, so that as air is admitted to the rear of the piston 3 by thegroove 32 there is a relatively short, slow travel of the piston 3 andthen a hard, rapid travel when it passes the port 3|. To this end thereis provided an annular recess 33 near the head 4 which communicates withthe groove 32.

Also provided in the handle I4 of the staple gun is an exhaustpassageway 10. This passageway communicates with the chamber 2| throughan exhaust port 1I formed in the sleeve I9. Another port 12 is formed inthe sleeve I9 and this latter port communicates with the passageway 22.

The operation of this valve arrangement is as follows. When the trigger28 is pulled and the button 26 thereby depressed the valve I8 is movedaway from the end of the sleeve I9 in the manner above described. Airthen passes from the chamber I5, through the passageway I6, into thechamber I1, past the valve I3 into the chamber 2|, through the port 12,into the passageway 22, through the port 3| and groove 32, and piles upbehind the piston 3 thereby moving it away from the head 4. When thepiston 3 moves past the port 3| a large amount of air enters behind thepiston and drives it hard and fast whereby the staple driver H picks upa staple 41 positioned in the slot 1 and drives it into the work. Suchdrive is cushioned bv the air cushion governed by vent nipple I2. Duringthis time the exhaust port 1I is blocked by the bushing 23.

On release of the trigger 2R the spring 21 returns the button 26 to theposition of Figure 2 and the spring 8 returns the piston 3 to itsstarting position. Air collected between the piston 3 and head 4 isexhausted out the port 3| (and groove 32), through the passageway 22.through the port v12 into chamber 2|, out port 1I (valve I8 now seatingagainst the end of sleeve I9) and iinally through the exhaust passageway10.

The large air chamber I5 permits the use of relatively small air linesthereby making the staple gun very easy to manipulate.

The staple driver 5 is pinned at one end to the piston 3 and the head ordriving end rides in a groove or slot 1. The slot 1 is closed by meansof a plate 34 which has beveled or cut away portions 35 (see Figure 4).The plate 34 when placed in position over the passageway 1 rests onshoulders 36a of the member 36 (this member forming the bottom of slot 1and may be considered as a base plate on which the plate 34 rests) andis held in position by the heads 31 of the bolts 38 resting in theindentations 35 (see Figure 3).

assenso This permits theV easy' removal andV replacement of the plate 34and the.v availability of the passageway21iand? the nose` andi feed'.mechanism in the eventastaple becomes jammed. particular feature of thenovel drive.- mecha,- n-ism-'just describede-and of the:` slotformingportions 354i and li--isl that by thisconstructionthe nose of" the gun,andthe driver 5 operating there'- in, can be changedwithout' changing'the stroke oil the piston.` Such! 'arrangements make my staple gunVquite adaptable'toa great many jobs that cant be handled byconventionalguns having a fixed staple drive condition. 'For example, byreplacing the staple driver 5 with a lon-ger member, andi bysubstitutinglongerv membersy for thel slot-forming portions 34- and.' 36,.azstaplergun having a `s'taple eiccti'ngfv nose which; protrudesz aconsiderable extent past the staple feed `track maybe achieved. 'A-gunfh'avingsuch afslong, relatively thin nose can be usedto-do'.stapling'in deep crevices notaccessible tothe ordinary gun. The amountby'which the length ofthe driver 5. can beincreasedis determined', seeFigure 2', by the distance between the iorward end of the, driver 5,when the piston '3 is in its retracted position, and theiA pointat`which.` the feed track brings staples intofposition.atthe'slot 1.

Itshouldalsofbe noted that I have so arranged the driver 5 a'ndpistonv3'that the driver is located or'pin-nedf to-the piston above its axis.By sopositioning the driver 5 I have provided a staple lgun whichl can'be' used in crevices and the like heretofore'not accessiblev to' stapleguns lof thisgeeral type;

VVThe staple feed comprises a staple track 40 having upstanding leg'members 40a' uponwhich rides a staple follower 46.' On 'top' of thestaple track I provide a cover @8 which: is longitudinally slidable` inaA second track'p'ositioned over the staple-'trackl andfwhich in turnhas a slot 50 which receives a projectingbossl 5I on the staplei'ollower ;461; One vend'of the cover 431' projects beyond the trackVand terminates in a hook shaped nger'g'ripBS- In order to feed thestaples l1Y uniformly, IY provide a spring 43, one'end of whichisattached near one end of the staple tracks l!!! and the body of whichrides over a sleeve l2A near the-other or staple feeding end of thetrack. The other'end of the spring 43 is attached to a pin 45v carriedbythev staple follower 4G; This spring lies' within the upst'anding legVmembers 40a of the track vlil and is straddled by the staples which areplaced about the track. Byl this means the springwhich feeds-the staplesis extremely long,

so that tension at all times is uniform. In loading the stapler, the'coverll' is pulled down along its track. This in turn pulls the staplefollower 46 towards one end of its track. Staples are then placed aboutthe track, the cover forced completely in-to its track, and the followermoved against the stack of staples by the spring 43; 'Ijhe slot 5I) inthe cover 4Q permits the coverA to be forced Yinto closed position eventhoughthe" follower must initially remainnear that end of its trackremoved from the gun nose, andj-it also permits the follower 46. tomovealong the track and feed the staples as so urged by the spring 43. It isto be understood that other means of feeding staples into the slot 1 infront of the driver 5 may be used.

By the above construction, a staple feeder is provided which permits theeasy loading of the whole staple track without the necessity of havingto completely remove any single part.

The staples 41 are continually fed into the nose ofthe gun and.positioned; in the slots 1 between the'members 34Jand 36 by the spring43 and follower 46:.: When the driver 5' has picked up one of thestaples and forced it out of `-the gun, another'v staple will be forcedinto the slot as the driver returns to its retracted position' as seenin Figure 2.

In order to permit the easy manipulation of my gun, I provide a swivelcoupling at the end of the chamber I5 and the handle I4 of the gun.

IThis vswivel connection consists of a nipple 51 screwed into the end ofthe chamber I5 and having a bore 58. A second nipple 59 is slidably p0-sitioned in the bore 58 of the nipple 51 with an annular head 6G withinthe chamber I5. The head 65 isf larger than the body portion 59, so ashoulder orf iiange is formed which projects out over the inner end ofthe nipple 51 and prevents the nipple 59 from sliding out. An airpassageway 6I is drilled through the nipple 59 and its outward end 62 isscrewed into a hose coupling 63.

Between the head 60 of the nipple 59 and the end of the nipple 51, Iprovide an annular gasket 64.

lirom the above, it is apparent that when pressure is built up in thechamber I5, appreciable torce is exerted against the head 65 of thenipple 59 attempting to drive it outwardly. However, this` pressureforces the head 6D against the gasket 5,4 and thus provides a tight sealbetween the nippleV 5,9 and the chamber I5. The nipple 59 may, however,be rotated within the nipple 51 and permit the easy movement of the gunduring its operation.

liroml the above, it is apparent that I have provided a portablepneumatic stapler which is compact and light and which may be used inremote and inaccessible spots and corners;

' The stapler may beused on air lines having diiterentjairv pressuresIby merely changing the vent nipple I2 (Figure 1) to accommodate thedinerent pressures. A novel feed is provided for the staples whichpermits a maximum of staples torbe loaded without any projections ridingwith the-staples which would catch in the clothing of the operator andtend` to destroy the feed.

The connection between the air line and the gun itselfA is rotatable andhence the gun may be handledand pla-cedV in diierent positions with aminimum of diiiculty.

' The passageway Which accommodates the staple driver 5` and the portthrough which the staples' are; fed into the nose of the gun are easilyaccessible by the mere removal of the two or more f Apositive: triggermechanism is provided which insures the complete and eicient stroke ofthe piston no matterV hnwr slowly the. trigger mechanismis.depressed.y

'i-Itzisztof b'e'understood that modifications and changes can be madein my invention-without departing fromthe scope and spiritV thereof, and

`wlsiile I. have shown my invention as embodied in structions other thanthose disclosed herein. Having thus described my invention, what I claimas new and what I desire to protect by United States Letters Patent is:

1. In a portable pneumatic stapler, staple drive mechanism comprising acylinder and cylinder head, a piston in said cylinder, means to admitcompressed air into said cylinder near said head and behind said piston,a staple driver secured to said piston, said driver comprising a flatplate pinned to said piston, nose structure for said stapler havingaslot therethrough adapted to receive said staple driver, means to feedstaples into said slot ahead of said driver when said piston is againstsaid head, means to cushion the driving stroke of the piston comprisingan outlet vent located towards that end of said cylinder which isopposite said cylinder head and which outlet Vent is closed before theend of the driving stroke, the stapler being substantially closed tc thepassage of air moved by said piston after said outlet vent is closed,and means to return said piston to said cylinder head when the supply ofcompressed air is cut oif.

2. The stapler of claim 1 in which said outlet vent is closed by saidpiston, and in which said return means comprises a relatively long andweak spring.

3. The stapler of claim 1 in which said piston is provided with a slotthicker than said blade and substantially Wider than said blade, saidblade being pinned to said piston within said last mentioned slot forlateral movement with respect thereto.

4. The stapler of claim 1 in which said nose structure comprises a baseplate, said slot being located in said base plate, and a cover platesecured to said base plate over said slot.

5. The stapler of claim 4 in which said base plate and said cover plateare removably secured to said stapler.

6. In a portable pneumatic stapler, staple drive mechanism comprising acylinder and cylinder head, a piston in said cylinder, means to admitcompressed air into said cylinder near said head and behind said piston,a staple driver secured to said piston, said driver comprising a atplate pinned to said piston, nose structure for said stapler having aslot therethrough adapted to receive said staple driver, means to feedstaples into said slot ahead of said driver when said piston is againstsaid head, and means to return said piston to said cylinder head Whenthe supply of compressed air is cut off, said nose structure comprisinga base plate, said slot being located in said base plate, and a coverplate secured to said base plate over said slot, said plates beingremovably secured to said stapler.

7. The stapler of claim 6 in which said flat plate is pinned to saidpiston to one side of the axis thereof.

8. In a portable pneumatic stapler, staple drive mechanism comprising acylinder and cylinder head, a piston in said cylinder, means to admitcompressed air into said cylinder near said head Vand behind saidpiston, a staple driver secured to said piston, said driver comprising aflat plate pinned to said piston, nose structure for said stapler havinga slot therethrough adapted to receive said staple driver, means to feedstaples into said slot ahead of said driver when said piston is againstsaid head, and means to return said piston to said cylinder head Whenthe supply of compressed air is cut off, said piston having a slotthicker than said blade and substantially wider than said blade, saidblade being pinned to said piston Within said last mentioned slot forlateral movement with respect thereto.

9. The stapler of claim 8 in which said last mentioned slot is offsetwith respect tc the axis of said piston.

10. The stapler of claim 1 in which said outlet vent is provided with anipple having an orifice therethrough, said nipple being removable fromsaid vent.

11. In a portable pneumatic stapler. staple drive mechanism-comprising acylinder and cylinder head, a piston in said cylinder, means to admitcompressed air into said cylinder near said head and behind said piston,a staple driver secured to said piston, nose structure for said staplerhaving a slot therethrough adapted to receive said staple driver, meansto feed staples into said slot ahead of said driver when said piston isagainst said head, means to cushion the driving stroke of the pistoncomprising an outlet vent located towards that end of said cylinderwhich is opposite said cylinder head and which outlet vent is closedbefore the end of the driving stroke, the stapler being substantiallyclosed to the passage of air moved by said piston after said outlet ventis closed, and means to return said piston to said cylinder head whenthe supply of compressed air is cut off.

12. In a portable pneumatic stapler, staple drive mechanism comprising acylinder and cylinder head, a piston in said cylinder, means to admitcompressed air into said cylinder near said head and behind said piston,a staple driver secured to said piston, nose structure for said staplerhaving a slot therethrough adapted to receive said staple driver, meansto feed staples into said slot ahead of said driver when said piston isagainst said head, means to return said piston to said cylinder headwhen the supply of compressed air is cut 01T, said nose structurecomprising a base plate, said slot being located in said base plate, acover plate disposed on said base plate over said slot, and means forremovably securing said plates tc said stapler.

ALBERT G. JUILFS.

REFERENCES CITED The following references are of record in the 'file ofthis patent:

UNITED STATES PATENTS Number Name Date 274,941 Heysinger Apr. 3, 18831,936,915 Polzer Nov. 28, 1933 1,939,632 Rand-all Dec. 12, 19332,219,739 Duncan Oct. 29, 1940 2,445,674 Kendall July 30, 1948 2,482,993Walker Sept. 27, 1949

